Matrix metalloproteinases (MMP) are a class of enzymes that degrade extracellular matrix in vitro and are upregulated in cancer, inflammation, and other human pathologies. Although inhibitor studies have been tested in clinical trials, they have not been effective against cancer and have had unacceptable side effects. These failed trials indicate that before effective therapies can be designed, the scientific community needs a more complete understanding of MMP biology and their normal physiological roles: what their functions are and what substrates they cleave. However, because there are 22 MMPs in mice and they can compensate for each other's loss, mutant analysis in mice does not give complete information about function. The fruitfly, Drosophila melanogaster, is an ideal organism for the study of MMPs, because they have only two MMPs in their genome. Previously mutations were generated in both genes, and the mutants have specific phenotypes indicating that the genes are non-redundant. In preliminary studies, two-hybrid screening identified candidate proteins that specifically bind to the dMmp1 hemopexin domain, and the physical interaction with one candidate has been confirmed by co-immunoprecipitation. In Specific Aim 1, the relationship between this candidate and dMmp1 will be determined in culture, in vitro, and in vivo;in preliminary studies, it appears to be proteolyzed in an Mmp1 -specific manner. Both Mmp1 and the candidate interactor may be important for the animal's response to septic wounding, and their roles in septic wound healing will be determined in Specific Aim 2. To gain a better understanding of MMP function in vivo, the cellular functions of the dMmp1 and its C-terminal hemopexin domain will be identified in the tracheal system in Specific Aim 3. (for lay people:) In order to grow and metastasize, cancers are believed to rely on proteins that break down and remodel body tissues. One such protein family, called MMPs, has been targeted by pharmaceutical companies for designing anti-cancer drugs, but these have had crippling side effects because we do not understand what MMPs normally do in the body. We will identify the functions and mechanisms of an MMP in a simple model organism in the hopes of learning how to make better cancer drugs.